Speed-control system for high-frequency generators



May 15, 192s. n 1,669,524

S. M. KINTNER SPEED CONTROL SYSTEM FOR HIGH FREQUENCY GENERATORS Filed NOV. 2. 1921 Patented May l5,

UNITED STATES PATIzN-'r orifice,

SAMUEL 1r. xINrNanMo-r PITTSBURGH, PENNSYLVANIA, lacercaron 'ro wnsrrne- Hoosn ELECTRIC a MANUFACTURING COMPANY, A conformaron or ammen- VANIA.

SPEIEI-CONTROLy SYSTEM FOR HIGH-FREQUENCY GENEBATOBE applicati@ inea november 2, 1921. serian no. naiss.

.viy invention relates to speed-regulating systems and more especially tosuch systems s may be employed in connection with highrecuency alternators.

flan object of my invention is to provide an improved system of speed-mntrol for machines requiring the utmost constancy in s eed.

PA. further object of my invention is to produce mechanical indications of small variations in .the frequency of a high-frequency source.

A still further object of my invention is to provide a speed or frequencyr-indicating` or controlling system in which a very high degree of sensitivity is secured by utilizing the heterodyne principle and rectifying the heterodyned current to obtain an alternating current in which thevariations in frequency may be accurately measured. y

With these and other objects in view, my invention consists in the combinations and in the details of construction hereinafter described and claimed and illustrated in the accompanying drawing, wherein:

Figure 1 is a diagrammatic view of circuits and apparatusemploying a preferred form of my invention;

Fig. 2 is a view showing the resonance curves of the beat-fre uency circuits including the actuating win ings of the relay.

In Fig. 1 is shown a driving motor 1, such, for example, as a direct-current motor comprising an armature member 2 having brushes 3 and t which are connected, by conductors 5 and 6, to a source of energy (not shown) through a resistor 7 l1li. field Winding 8 and a resistor 9 are serially included in a circuit which is connected in shunt around the resistor and the motor 1. Relays 11 and 12 may be selectively rendered effective to shunt resistors 7 and 9, respectively, for controlling the speed of the motor, as hereinafter explained.

A high-frequency alternator 13,'having a normal frequency fm which it is desired to maintain constant within as close limits as possible, comprises armature windings 14 and a rotor member-15 Which is operatively connected` to the motor armature 2 by means Pein 27 of a common shaft 16. The armature Windings 14 are connected. by conductors 1'? and 18. to a worlr circuit 19 which may be a ciru cuit utilizing).r the alternator 13 as a source of high-frequency power for 'transmitting radio signals or as a heterodyning source in a Wireless receiving station (not shown).

As a means for securing a small amount of high-frequency energy from the alternator for energizing my speed-controlling device, I have connected a resistor 20 in shunt relation to the conductors 17 and 18, though it is apparent that an inductance coil or a series of condensers may be employed in lace of the resistor 20.

The resistor 20 is tapped by a pair of circuits 21 and 22 comprising coupling coils 23 and 24 and condensers 25 and 26, respectively, and carrying currents of'generator frequency ,423' by reason or the adjustable connections 27, 28 and 28, 29 to the resistor 20. In the embodiment shown, no attempt is made to secure resonant conditions in the circuits 21 and 22, as it is frequently best to have them operating' under non-resonant conditions. i

The circuits 21 and 22 are heterodyned, respectively, with suitable constant-frequency sources 30 and 31, such, for example, as thermionic oscillation-generator systems of great constancy of frequency or the like, which are inductively associated with the coils 23 and 24 through coupling coils 32 and 83, respectively. @ne of the heterodyning sources, as 30, has a frequency which is greater than that of the alternator 13 by a small amount F3, While the other heterodyne source, as 31, has a frequency `which is smaller than that of the alternator 13 by a similar amount F, whereby similar beatfrequencies F, are produced in the cir cuitsv 21 and 22, but with this distinction that one is decreased while the other is increased upon a departure of the alternatorl 13 from the constant frequency fla.

The high-frequency currents with beatfrequency envelopes, obtained in circuits 21 and 22, are convertedinto alternating-currents of the beat frequency F, by means of a pair, of thermionic tubes 34 and 35 come4 pricing anodes 36 and 36', cathodes 37 and 37', and id members 38 and 38', respectively. e cathodes 37 and 37v may be energized from a common source of energyv 6 441 through rheostats 42 and 43, respectively.

The grid circuits of the tubes 34 and 35 are connected across the condensers 25, 26`

of the circuits 21, 22, through blockin con- 0 the movable colls 54, 55 of a second dynationary and movable coils 51, 52,`of a dynamometer relay 53. Similarly, a platefila. mentD circuit for the tube 35 includes the' source of ener 49 and the stationary and mometer relay 56, which is mounted upon the same shaft 57 as the relay 53, the two relays producing opposing torques. The relay shaft 57 carries a switch arm 58 which coacts with the stationary contact members 59 and 61 to effect the operation ofthe relays 11 and .12 respectlvely, thereby acerating or retardmg the speed of the motor.

The stationary contact member 59 is conveniently connected to one terminal of the source of energy 41 through actuating winding 62 of the relay 11 and ground, while the stationary contact membenl is similarly connected' through actuating winding 63 of therelay 12 and ground. The movable contact arm 58 is connected by conductor 64 to the remaining terminal of said source of energy 41.

The actuating windings 51 and 52 of the relay 53 are included in a circuit' 48, which is resonant at a frequency F1, somewhat less than the beat-frequency F3, and which also includes a serially connected condenser 664 and a by-pass inductance coil 67, the latter being connected across the series-connected windinos 51 and 52 and the condenser 66. Similallly, the remaining actuating windings 54 and 55 of the` relay 56 are included in a circuit which is resonant at the same frequency F, and which also includes a seril ally connected condenser 68 and a by-pass inductance c/oil 69, the latter being connected across the series-connected windings 54 and and the condenser 68.

In operation, the speed-controllingrelays 11 and 12 are normally de-energized when the alternator frequency f1, is at its correct ce amount c. It is at once apparent that the ratio of the change in freque'nc in the beatfrequency circuits 48 and 50 1s very much greater than that in the circuit of the alter- 'cir-cuit 48 to increase to a value z', while the current lm, in circuit 50 decreases to a value 2, as lindicated in Fig. 2. The contact arm- 58 is acuated, by the resultant unbalancing of the relays 53 and 56, to engage contact 61, which, in turn, energizes the relay 12 and reduces the speed of the drivin@r motor 1. ln a similar manner, the relay 11`is energized to increase the speed of the'motorv A l if the alternator frequency decreases by the small amount a.

It will be understood that my invention,.

in its broader aspects, is not to be limited to I the specific heterodyning sources indicated at 30 and 31 inasmuch as they are intended to represent any available source and one of 'them could be derived from the incoming signaling currents of. a radio-receiving station.

The extremely high sensitivity' of my speed-control system may be illustrated in the following example. It will be assumed for instance, that the generator frequency is f=20,000 cycles per second and that the local heterodyne-source, fr uencies are 20,- 100 and 19,900, respective y. Then, upon the interaction of the several currents and the rectification in the thermionic devices 34 and 35, beat-frequency currents of F3= l100 cycles per second are normally caused to traverse the circuits 48 and 50. The normal beat-frequency F3, it will be noted, is thus 1/2 of 1% of the alternator frequency f1`.

Furthermore,A it is apparent that a charge in the alternator frequency of 1/2 of 1% causes a variation in the beat-note frequency of 100%. f

Assuming that a condition exists in the resonant circuits wherein a 5% change in frequency causes a sucient change in current to actuate the relay, it can readily be seen that actuating forces necessary to operate the relay are producedy with 1/40 of 1% change in the' alternator frequency. Thus, while utilizing resonantI circuits sensitive only to 5% frequency variations, l am able,

'by my invention, to maintain/the frequoency of the high-frequency alternator constant to within'plus or minus1/40 of 1% of the desired frequency. f

.While Ihave shown but one embodiment of my invention, for the purpose of describing the same and illustrating its principles, it is apparent that various changes and modifications may be made therein without departing from the spirit thereof and I desire, therefore, thatA only such limitations rent generator frequency for impressing" corrective influences uponA said ynamo-electric machines substantially in synchronism frequencies of said oscillation generators with said tluctuations.v

10. In an 'electrical system, the combination with a source of power and an altermating-current generator driven thereby, of separate circuits derivingy energy from said generator, an oscillation generator associated with each circuit and adapted to produce currents of similar beat-frequencies, the

being, respectively, above' and below that of said alternating-current generator, means for deriving alternating currents of beatfrequency romsaid separate circuits and means responsive to relative 'changes .in the currents Y,

' cillation generators being, respectively, above and below that of said alternating-current generator, means associated with each of said separate circuits for deriving alternating currents of beat frequency therefrom, a pair of translating'circuits operatively associated with said last-mentioned means and means associated with said translating circuits for counteracting variations in the relative beatfrequencics of the current in each translating circuit incidenty to changes in the alternating-currents generator frequency.

V12. A Y regulator system comprising a source of power, an alternating-current generator driven thereby, separate circuits deriving energy from said generator, an oscillation generator associated with each circuit and adapted to produce currents of similar beat-frequencies, the frequencies of said oscillation generators being, respectively, above and below that 'of said alternating-current generator, means operatively connected to each of'said separate circuits for deriving component currents of beat-frequency there c from, means associated with said last-mentioned means, whereby variationsin the rel'- ative beat-frequencies f said component currents incident to variation in the lalternating-current generator` frequency are translated into corresponding current variations, and control mechanism sensitive to said cur.-

rent variations for counteractingthe alterhating-current generator, frequency variations: Y

13.v In a regulator system, a generator of ultra-audio-frequency cui-ren a pair of circuits deriving energy there rom, heteroincassi dyning means associated with each c ircuitv being, respectively, above and below that of said generator, rectifying means associated wvith each circuit for producing variable currents of beat frequencies therefrom, a pair of circuits each including a resonant circuit associatedwith said last-mentioned means, said circuits being resonant to a frequency slightly different from said beatfrcquency,whereby variations in the said beat-frequencies incident to uctuations in 1 said generator frequenc variations in the am litu e of the beat currents traversing sai resonant circuits, and means responsive to saidgbeat-current variations tending to correct said generator requency variations.

' 14. In a regulator system, av generator of ultra-audio-frequency currents, a pair of circuits deriving ener dyning meansl associate? producing similiar beat-frequencies therein,

the 'frequency of the heterodyning meansA being respectively above and below that of cause opposite.

therefrom, heterowith each circuit for said generator, a pair of three-electrode tubes having plate-filament and grid-lament-circuits, meansjfor coupling said grid-filament circuits to said inst-mentioned circuits,

means lincluded in each gridI circuit for causing the beat-frequencies therein to be translated into lcurrents'of beat frequency in the associated plate-filament circuit, resonant means included in each plate-lilament circuit, said resonant means being tuned to frequencies slightly dierent from said beat frequencies, whereby variations inA said heat frequencies incident to fluctuations in salti generator frequency causes variations in opposite directinnsv in the amplitude of the' beatlcurrents in said pair of resonant means,

and current-responsive means associated with said resonant means for correcting said generator frequency variations.

15. In a-regulating system, the conibination withfa source of power and an ultraaudio uency generator, of a pair of circuits deriving ener therefrom, heterodyning'means associated with each circuit for producing similar beat-frequencies, ythe A:frequencies of the heterodyning means being; respectively, above and below the generator frequency, a pair of evacuated elec tric devices lhaving plate-iilament circuits,

'means jfor couplingv said grid-filament circuits to said first-mentioned circuits, means included in each grid-iilament circuit forcausing the beat-frequencies therein to be. translated into alternating currents of beatfrequency ini-each' plate-filament circuit, a parallel-resonant wcircuit Vincluded in each late-filament circuit and tuned 'to sucl di" uencies that variations in said beat frequencies. caused by 'fluctuations 1n said generator frequency produce opposite variations in the am litude of the beat currents in said para lei-resonant circuits, and switching mechanism coacting with said source of power, whereby said current variations tend to correct said generator frequency fluctuations. y

16. A frequency-sensitive instrument including a pair of current-actuated motor devices mechanicali opposed to each other, circuits, one for eac of said devices, the currents in said circuits being normally of the same irequenc7 and normally keepin said devices in equi ibrium, and means, inc uding resonance devices in said circuit, whereby, upon the departure fromvnormal frequency,

4one of said currents will increase and the other other decrease. v

In testimony whereof, I have hereunto subscribed* my name this 22nd day of October, 1921.

SAMUEL M. KNTNER. 

